1. Field of Invention
The present invention relates generally to the field of cable feed apparatus, and more particularly, but not by way of limitation, to a safety apparatus for severing cable.
2. Description of the Prior Art
In the petroleum industry, it is often necessary to position electrically responsive equipment down the bore of an oil well or the like, an example of which is electric submersible pump or the like which are lowered beneath the surface of the earth secured to a tubing string for pumping liquid from the well. In order to supply electrical energy to down-hole electrical equipment, power cables run from an electrical power source located above-ground to the down-hole device. This necessitates the utilization of very long electrical cables, and cable feeding systems have been devised to feed such cables upon demand to the down-hole equipment as it is lowered into the well bore.
The down-hole electrical equipment under consideration is usually supported from above ground by a plurality of pipe sections threadingly interconnected to form a well string. It is conventional practice to attach the electrical cable leading to the down-hole electrical equipment to the side of the supporting well string, and to position a rotatable spool wound with electrical cable in close proximity to the bore head so as to feed the electrical cable as required to follow the down-hole electrical equipment. Also, the spool is used to take up the cable when the down-hole electrical equipment is removed from the well bore.
In the cable feed system described, a problem of great magnitude is encountered when the supporting well string breaks. In consequence thereof, the electrical cable spool is suddenly attached to a free-falling portion of the well string, and an extremely hazardous condition occurs. The great weight and kinetic energy of the falling portion of the well string pulls with great force upon the cable spool, yanking the spool in a perilous manner free from its supports, and hurtles the spool toward the bore head. Property damage by this catastrophic occurrence is always forthcoming, and even more unfortunate, persons have been fatally injured as the spool is practically unstoppable in its path of wreckage.